In my co-pending application, whose disclosure is hereby incorporated by reference, I teach a sleeve assembly for repairing a leak in the wall of a steel pipeline for conveying oil. This assembly involves mounting a pair of semi-circular steel shells around the line and tightening or pressing them into load-applying engagement with the circular pipe wall. One of the shells carries a protruding annular seal member which seats in a recess formed by the inner surface of the shell. The seal member surrounds the leaking aperture and seals around it to prevent fluid escape between the shell and the pipe. Once the seal member has sealed, the stressed shells are welded longitudinally to create a permanent, full encirclement sleeve.
In connection with tightening the shells against the pipe it is desirable:
That, as much as possible, the load being applied by the tightener be distributed uniformly to the shells. If the load is relatively concentrated at a point, there is a risk of denting the sleeve and pipe; PA1 That the tightener used be adapted for use with shells and pipe of different curvatures or diameter; and PA1 That the tightener is powered by a fluid cylinder so that the extent of loading may conveniently be monitored. PA1 a scissor clamp having arms pivoted at a first end and having means at the second end for engaging the two ends of a chain loop; and PA1 a fluid-actuated cylinder disposed substantially perpendicularly to the arms when the latter are together, said cylinder carrying a support plate at one end, the rear surface of the clamp's first arm abutting the support plate, the cylinder being connected to the clamp's second arm between its ends, whereby the cylinder may bias the second arm toward or away from the supported first arm.